In their defense... you did just tell them u wanted to build a race car to race in parking lots man. With that being said. If I was going to build a car made for short straight away blasts and hait pin turns id probably be looking into an engine that was high compression , small runner head with a dual plane intake and a big set of headers. OH and id probably gear the shit out of if. Not only will a shit load of gear make it accelerate like a bat out of hell but if you release the gas peddle it will give you tons of brake effect.

If i were you id lighten the car to a feather
put 4.56-4.88 gears in the rear.
replace your wheels , tires and put the biggest baddest brakes i could find on it.
go coilovers on all 4 corners , replace your entire frnt and rear suspension and take it from there. I say this because all the power wount help you if u cant make the turn at the end of your straight aways. Then again I doubt id consider a fox body at all for that kinda racing... but that just my personal opinion.